Second, there isn't anything specifically Ranorex related in that stack trace, just a couple of references to MS Windows Automation Peers object. This could be a case where your AUT has a bug that is only brought forward when Ranorex is manipulating the UI. Do you get the same thing when you use Ranorex Spy on your AUT? Have you tried Microsoft's Spy tool?

Hi Vamsi,
Thank you for the additional information.
I'm afraid we need to analyze this problem directly within our controlled environment. Please do let me know if you could send us your application under test.